Running Additional Programs At Boot Time - Red Hat ENTERPRISE LINUX 3 Reference Manual

6
As illustrated in this listing, none of the scripts that actually start and stop the services are located in
the
/etc/rc.d/rc5.d/
pointing to scripts located in the
the directories so that the runlevels can be reconfigured by creating, modifying, and deleting the
rc
symbolic links without affecting the actual scripts they reference.
The name of each symbolic link begin with either a
on that runlevel, while those beginning with an
The command first stops all of the
init
/etc/rc.d/init.d/ command
killed. It then starts all of the
.
start
Tip
After the system is finished booting, it is possible to log in as root and execute these same scripts
to start and stop services. For instance, the command
Apache HTTP Server.
Each of the symbolic links are numbered to dictate start order. The order in which the services are
started or stopped can be altered by changing this number. The lower the number, the earlier it is
started. Those symbolic links with the same number are started alphabetically.
Note
One of the last things the
for system customization. Refer to Section 1.3 Running Additional Programs at Boot Time for more
information about using the
After the command has progressed through the appropriate
init
script forks an
/etc/inittab
allocated to the runlevel. Runlevels 2 through 5 has all six virtual consoles, while runlevel 1 (single
user mode) has one and runlevels 0 and 6 have none. The
cation pathways to tty devices
and password and initiates the login process.
In runlevel 5, the
/etc/inittab
ecutes the preferred X display manager
/etc/sysconfig/desktop
Once finished, the system is operating on runlevel 5 and displaying a login screen.

1.3. Running Additional Programs at Boot Time

The
/etc/rc.d/rc.local
runlevels. Adding commands to the bottom of this script is an easy way to perform necessary tasks
like starting special services or initialize devices without writing complex initialization scripts in the
/etc/rc.d/init.d/
5. Refer to Section 5.3.11
6. Refer to Section 7.5.2 Runlevel 5 for more information about display managers.
directory. Rather, all of the files in
/etc/rc.d/init.d/
stop
symbolic links by issuing
S
program executes is the
init
file.
rc.local
/sbin/mingetty
5 , sets their modes, prints the login prompt, accepts the user's username
runs a script called
6
—
file.
script is executed by the
directory and creating symbolic links.
for more information about
/proc/tty/
Chapter 1. Boot Process, Init, and Shutdown
/etc/rc.d/rc5.d/
directory. Symbolic links are used in each of
or an . The
K S
are started.
S
symbolic links in the directory by issuing the
K
command, where
/etc/rc.d/init.d/ command
/etc/rc.d/init.d/httpd stop
/etc/rc.d/rc.local
process for each virtual console (login prompt)
/sbin/mingetty
/etc/X11/prefdm
, , or
gdm kdm xdm
command at boot time or when changing
init
tty
are symbolic links
links are processes that are killed
K
is the process to be
command
file. This file is useful
directory for the runlevel, the
rc
process opens communi-
. The
prefdm
, depending on the contents of the
devices.
stops the
script ex-